U.S. patent application number 13/228100 was filed with the patent office on 2012-03-22 for method for determining the length of the route travelled by a vehicle.
This patent application is currently assigned to KAPSCH TRAFFICCOM AG. Invention is credited to Katharina Kaes, Oliver Nagy, Jasja Tijink.
Application Number | 20120072108 13/228100 |
Document ID | / |
Family ID | 43587052 |
Filed Date | 2012-03-22 |
United States Patent
Application |
20120072108 |
Kind Code |
A1 |
Kaes; Katharina ; et
al. |
March 22, 2012 |
METHOD FOR DETERMINING THE LENGTH OF THE ROUTE TRAVELLED BY A
VEHICLE
Abstract
A method for determining the length of the route travelled by a
vehicle using a position measuring device that records positions of
the vehicle and a digital road map, which is composed of road
segments of known segment lengths. The method including recording
positions of the vehicle on the route by means of the position
measuring device, matching the recorded vehicle positions to a
sequence of road segments, and determining the route length from
the segment lengths of these road segments, wherein from the angle
between at least two consecutive road segments and an assumed road
width of the two road segments, a turn-off route of the vehicle
from the one road segment into the other road segment is
calculated. The calculated turn-off route is taken into
consideration in the determination of the route length.
Inventors: |
Kaes; Katharina; (Wien,
AT) ; Tijink; Jasja; (Breitenfurt, AT) ; Nagy;
Oliver; (Wien, AT) |
Assignee: |
KAPSCH TRAFFICCOM AG
Wien
AT
|
Family ID: |
43587052 |
Appl. No.: |
13/228100 |
Filed: |
September 8, 2011 |
Current U.S.
Class: |
701/416 |
Current CPC
Class: |
G01C 22/00 20130101;
G07B 15/063 20130101 |
Class at
Publication: |
701/416 |
International
Class: |
G01C 21/34 20060101
G01C021/34 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2010 |
EP |
10 450 146.5 |
Claims
1. A method for determining a length of a route travelled by a
vehicle using a position measuring device that records positions of
the vehicle, and a digital road map including road segments of
known segment lengths, the method comprising: recording positions
of the vehicle on the route by the position measuring device;
matching the recorded vehicle positions to a sequence of road
segments; calculating, from an angle between at least two
consecutive road segments and an assumed road width of the two road
segments, a turn-off route of the vehicle from said one road
segment into said other road segment; and determining the route
length from segment lengths of the sequence of road segments and
the calculated turn-off route of the vehicle.
2. The method according to claim 1, wherein at least one road
segment of the digital road map represents a road with at least two
lanes assigned to opposing travel directions, and wherein
calculating a turn-off route comprises calculating a turn-off route
to/from a lane assigned to the direction of travel of the
vehicle.
3. The method according to claim 1, wherein at least one road
segment of the digital road map represents a road with at least two
lanes, of which at least one lane is assigned to a specific
turn-off direction, wherein calculating a turn-off route comprises
calculating a turn-off route to/from a lane assigned to the
turn-off direction of the vehicle is calculated.
4. The method according to claim 3, wherein the turn-off route is
calculated as a polygonal line.
5. The method according to claim 3, wherein the turn-off route is
calculated as an arc of a curve.
6. The method according to claim 1, wherein the assumed road width
is taken from the digital road map.
7. The method according to claim 1, wherein a predetermined value
is assumed as the road width.
8. The method according to claim 1, wherein possible turn-off
routes between road segments of the digital road map are
pre-calculated and stored in a table, from which the respective
turn-off route to be taken into consideration between the two road
segments is then taken.
9. The method according to claim 1, wherein a turn-off route
between two road segments is calculated and taken into
consideration in determining the route length, when the angle
between the two road segments exceeds a predetermined value.
10. The method according to claim 1, wherein turn-off routes over
the course of the travelled route are calculated and taken into
consideration in determining the route length, when a number of the
turn-off routes exceeds a predetermined number, or when a sum of
the turn-offs exceeds a predetermined value.
11. The method according to claim 1, wherein no turn-off routes are
calculated and taken into consideration in determining the route
length between more than two consecutive road segments with
approximately equal angles alternating in respective turn-off
direction.
12. The method according to claim 1, wherein the turn-off routes
are only calculated and taken into consideration in determining the
route length, for road segments in specific areas of the digital
road map in urban areas.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority to European Patent
Application No. 10 450 146.5, filed on Sep. 17, 2010, the contents
of which are hereby expressly incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for determining
the length of the route travelled by a vehicle using a position
measuring device that records positions of the vehicle and a
digital road map, which is composed of road segments of known
segment lengths.
BACKGROUND
[0003] The measurement of the distance or length of route travelled
(covered) by a vehicle is one of the bases of toll calculation in
modern road toll systems that are based on digital map material.
For this purpose, vehicle positions ("position fixes") determined
by satellite navigation, for example, are matched to the road
segments of the digital road map by "map matching" and the distance
travelled is determined from the lengths thereof. However, this
procedure is subject to a significant amount of inaccuracy, since
it is based on idealised assumptions: the road segments of
currently available digital road maps represent real roads in an
idealised linear form for the purpose of simplifying and reducing
the storage requirements. In this case, the segment lengths of the
road segments are respectively defined between the intersection
mid-points of the real roads.
SUMMARY
[0004] The applicants have recognised that a significant
measurement error will accumulate if a vehicle does not follow
these idealised intersection mid-points. Accordingly, the present
invention uses the real road width and in particular takes inside
or outside bends past the intersection mid-points. The invention is
directed to a novel method that takes into consideration the
imaging errors of idealised digital road map material and on the
basis of this road map material allows a more accurate route length
determination than the known methods.
[0005] In some embodiments, the invention calculates, from an angle
between at least two consecutive road segments and an assumed road
width of the two road segments, a turn-off route of the vehicle
from said one road segment into said other road segment. The
turn-off route is taken into consideration in the determination of
the route length.
[0006] Working from idealised linear road segments of a digital
road map, the method according to the invention calculates a
realistic model of the road network by entering real turn-off
routes at road intersections into the length determination for the
first time. As a result, a significantly more accurate
determination of the route covered by the vehicle can be
obtained.
[0007] In some embodiments of the present invention, the at least
one road segment represents a road with at least two lanes assigned
to opposing directions of travel is distinguished in the
calculation of the turn-off route to/from this road segment the
turn-off route to/from the lane assigned to the direction of travel
of the vehicle.
[0008] In some embodiments of the invention, at least one road
segment representing a road with at least two lanes, of which at
least one is assigned to a specific turn-off direction is
distinguished in the calculation of the turn-off route to/from this
road segment the turn-off route to/from the lane assigned to the
turn-off direction of the vehicle. Thus, both variants take into
consideration not only the position of the road segments relative
to one another, but also the movement history ("track") of the
vehicle for the selection and calculation of the turn-off route to
be applied between road segments. The route length determination
can thus be structured even more accurately.
[0009] In some embodiments of the invention, the turn-off route can
be calculated approximately as a polygonal line resulting in a
faster calculation time. Alternatively, the turn-off route can be
calculated as an arc of a curve, which provides an even more
accurate approximation of the real road parameters.
[0010] If the digital road map contains details concerning the road
width, the details can be taken directly from the road map.
However, a predetermined value may be assumed as the road width so
that the method can be conducted on the basis of conventional road
maps with linearly digitised roads.
[0011] In some embodiments, possible turn-off routes between road
segments of the digital road map are pre-calculated and stored in a
table, from which the respective turn-off route to be taken into
consideration between two road segments is then taken. This enables
the processing of the method to be accelerated.
[0012] Further embodiments of accelerating the method for real-time
processing, for example in an OBU, a toll billing server, or a map
matching server are comprised in one or more of the following:
[0013] a. a turn-off route between two road segments is only
calculated and taken into consideration when the angle between
these exceeds a predetermined minimum value;
[0014] b. the turn-off routes over the course of the travelled
route are only calculated and taken into consideration when their
count exceeds a predetermined minimum number or when their sum
exceeds a predetermined minimum value;
[0015] c. no turn-off routes are calculated and taken into
consideration between more than two consecutive road segments,
between which angles lie that are respectively approximately equal,
but alternate in their turn-off direction; and/or
[0016] d. the turn-off routes are only calculated and taken into
consideration for road segments in specific areas of the digital
road map, preferably only in urban areas.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows sections of a road network modelled by a
digital road map, in which vehicles travel exemplary routes,
according to some embodiments of the present invention; and
[0018] FIG. 2 shows in detail the method of the invention for
determining the route lengths covered at a turn off in a road
network, according to some embodiments of the present
invention.
DETAILED DESCRIPTION
[0019] FIG. 1 shows a vehicle 1 that moves on exemplary roads 2-9
of a sectionally represented road network 10. Two possible routes
that can be travelled by the vehicle 1 in the road network 10 are
shown at 11 by a dotted line and at 12 by a bold line.
[0020] The vehicle 1 is equipped with an onboard unit (OBU) 13 that
continuously determines its position -- e.g. with the aid of
satellite navigation or by other methods. Three exemplary vehicle
positions ("position fixes") 14 are shown for illustration. The
vehicle positions 14 are recorded by the onboard unit 13 or
transmitted by this to a central control unit (not shown) of a road
toll system to be recorded.
[0021] The road network 10 is modelled by a digital road map 15,
which is stored e.g., in the OBU 13, in the control unit or a map
matching server of the road toll system. The digital road map 15
comprises linear road segments s.sub.2-s.sub.9 (see dot-dash
lines), which are respectively matched to roads 2-9 and represent
these in an idealised linear form. It is understood that curved
road courses can be represented by a polygonal-line-type sequence
of road segments, as illustrated in the case of road segments
s.sub.4 and s.sub.5.
[0022] The road segments s.sub.2-s.sub.9 are respectively defined
in the digital road map 15 between junction or intersection
mid-points m.sub.2, 7, 8, m.sub.8, 9, 6, m.sub.2, 3, m.sub.3, 6, 4,
m.sub.4, 5 etc. of the adjoining roads, i.e. without taking into
consideration the width b of the roads 2-9. As a result, the
distance (route length) covered (travelled) by the vehicle 1 on
route 11 deviates in reality from the mere sum of the segment
lengths of the road segments s.sub.9, s.sub.8, s.sub.2, s.sub.3,
s.sub.4 and s.sub.5, as can be seen from FIG. 1. The behaviour is
the same with the exemplary return route 12.
[0023] In the case of two-lane roads, as shown in FIGS. 1 and 2,
the deviation between the length of the route 11 or 12 and the
length of the road segments s.sub.9, s.sub.8, s.sub.2, s.sub.3,
s.sub.4 and s.sub.5 is dependent not only on the turn-off routes of
the vehicle 1 when turning from one road segment into the next, but
also on the direction of travel of the vehicle 1, since individual
lanes 16-19 of the roads 2-9 can be assigned to specific travel
and/or turn-off directions 20. FIG. 2 shows this in detail on the
basis of the exemplary intersection m.sub.2, 3 of roads 2, and
their road segments s.sub.2, s.sub.3.
[0024] The length L' of the route covered when turning off from
road 2 into road 3 determined from the road map 15 would be
L'=l.sub.2+l.sub.3 (1)
where: [0025] l.sub.2 is the segment length of road segment s.sub.2
of the digital road map 15 for road 2 and [0026] l.sub.3 is the
segment length of road segment s.sub.3 of the digital road map 15
for road 3.
[0027] Taking into consideration an assumed width b.noteq.0 of
roads 2, 3 e.g. of 6 m and an angle .alpha..noteq.0 between the two
roads 2, 3 or road segments l.sub.2 and l.sub.3, the length L' is
to correct the respective turn-off route A of the vehicle l --
e.g., when turning off from road 2 into road 3. The actual or real
length L can be set at
L.sub.corr=l.sub.2+l.sub.3+A (2)
where [0028] A is the length of the turn-off route as correction
term, i.e. positive in the case of lanes 16, 19 on the outside of
the bend and negative in the case of lanes 17, 18 on the inside of
the bend.
[0029] For example, if the turn-off route A is approximated as the
arc of a curve, both roads 2, 3 have the same width b and the angle
.alpha.amounts to 90.degree. , for example, then the turn-off route
A on the "inside bend" is
A = .pi. 8 b - b ( 3 ) ##EQU00001##
and on the "outside bend" is
A = .pi. 8 b ( 4 ) ##EQU00002##
[0030] If the roads 2, 3 do not have the same predetermined width
b, for example, if these can be taken separately from the digital
road map 15 for each road segment s.sub.2, s.sub.3 or for specific
types of road segments such as trunk roads, major and minor roads,
the turn-off route A can be approximated, for example, as an arc of
an ellipse. Other types of curve arc approximations, e.g. typical
steering radii of vehicles, can be assumed and taken into
consideration.
[0031] In simplified embodiments the turn-off route A could also be
merely approximated by a polygonal line, e.g. by the shown diagonal
d. With an angle .alpha.=90.degree. and a constant road width b for
the inside bend (-) or outside bend (+) the turn-off route A would
then be
A = ( 1 - 2 2 2 .+-. 1 2 ) b ( 5 ) ##EQU00003##
[0032] For turn-off angles a other than 90.degree. the turn-off
route A can be calculated in the same way by corresponding
trigonometry.
[0033] As shown in FIGS. 1 and 2, particularly in the case of
multilane roads, in which the lanes 16-19 are respectively assigned
to a specific direction of travel 20, the turn-off route A is
dependent on the respective direction of travel 20 of the vehicle
1. In the case of roads 21 with multiple lanes 22, 23 in the same
direction of travel, of which e.g. one lane 23 is assigned to a
specific turn-off direction, as here lane 23 for the left turn-off
into lane 18, a corresponding turn-off route A can be taken into
consideration in the same way.
[0034] It is also possible in principle to pre-calculate all
possible turn-off routes A in a road network 10 between roads 2-9,
i.e. road segments s.sub.2-s.sub.9 of the digital road map 15, and
store them in a table of a data bank of the OBU, the toll billing
server and/or a map matching server. Such a table can be added to
the digital road map 15, for example, and can even be distributed
with the map. When determining the route length L, it is possible
on the basis of the road segments s.sub.2-s.sub.9 used by the
vehicle 1 to take the respective turn-off routes A to be applied
between these segments from the pre-calculated table and take these
into consideration.
[0035] Further optional possibilities for an acceleration or
simplification of the method in offline or online ("real time")
implementations include:
[0036] a turn-off route A between two road segments s.sub.2-s.sub.9
is calculated and taken into consideration when the angle .alpha.
between these exceeds a predetermined minimum value;
[0037] the turn-off routes A over the course of the travelled route
11, 12 are calculated and taken into consideration when they exceed
a predetermined minimum number or the sum thereof exceeds a
predetermined minimum value;
[0038] no turn-off routes A are calculated and taken into
consideration between more than two consecutive road segments
s.sub.2-s.sub.9, between which angles a lie that are respectively
approximately equal, but alternate in their turn-off direction;
and/or
[0039] the turn-off routes A are calculated and taken into
consideration for road segments s.sub.2-s.sub.9 in specific areas
of the digital road map 15, preferably only in urban areas.
[0040] The outlined method for determining route length can be
applied in any suitable processing point of a road toll system,
e.g. in OBUs, which have their own stored road map material 15 and
determine the covered route length L therefrom; or in central toll
billing servers, which obtain raw position data (position fixes or
tracks) from OBUs and match these to a digital road map 15 (map
matching); or in separate map matching server farms, which conduct
the computer-bound map matching for OBUs or toll control units.
[0041] Consequently, the invention is not restricted to the
represented embodiments, but covers all variants and modifications
that fall within the framework of the attached claims.
[0042] It will be recognized by those skilled in the art that
various modifications may be made to the illustrated and other
embodiments of the invention described above, without departing
from the broad inventive scope thereof It will be understood
therefore that the invention is not limited to the particular
embodiments or arrangements disclosed, but is rather intended to
cover any changes, adaptations or modifications which are within
the scope and spirit of the invention as defined by the appended
claims.
* * * * *